1. Field of the Invention
This invention relates to a data recording method suitably applied to record data of a compact disk format onto a magneto-optic disk, for example, of the ISO format.
2. Description of the Related Art
Conventionally, ISO (International Standardization Organization) formats for 3.5- and 5-inch magneto-optic (MO) disks have been proposed. FIG. 1 shows a sector format for a 5-inch magneto-optic disk of the 512 bytes/sector type wherein a CS (continuous servo) system is employed as a servo system.
Referring to FIG. 1, reference character "SM" denotes a sector mark. The pattern of the sector mark "SM" has a 5-byte length and is "1.sup.10 0.sup.6 1.sup.6 0.sup.14 1.sup.6 0.sup.6 0.sup.6 1.sup.10 0.sup.2 1.sup.1 0.sup.2 1.sup.1 0.sup.2 1.sup.1 0.sup.1 ". Here, 1.sup.a and 0.sup.b are channel bits and represent that "1" and "0" appear continuously by quantities a and b, respectively. Reference characters "VF01" to "VF03" denote each a VFO sink (PLL). The patterns of them are continuous patterns and individually such as follows:
______________________________________ VF01 - 010010010010 . . . 0010 (12 bytes) VF02 - 100100100100 . . . 0010 (8 bytes) 000100100100 . . . 0010 (8 bytes) VF03 - 010010010010 . . . 0010 (12 bytes) ______________________________________
Reference character "AM" denotes an address mark. The pattern of it has a 2-byte length and is "0100100000000100".
Reference characters "ID1" to "ID3" denote each an address and have a same pattern. Each of the addresses "ID1" to "ID3" includes two bytes for a track number and one byte for a sector number recorded in the (2, 7) modulation. It further includes a CRC of 16 bits introduced therein and recorded in the (2, 7) modulation. A generating function of it is EQU G(x)=x.sup.16 +x.sup.12 +x.sup.5 +1
Reference character "PO" denotes a postamble. A pro-format area thus ranges from the sector mark "SM" to the postamble "PO".
Subsequently to the pre-format area, "TOF", "FLAG", "GAP" and "ALPC" are disposed. "TOF" corresponds to a mirror face which has no groove thereon. "FLAG" denotes a flag representing that writing has been performed. A pattern to be set includes repetitions of "100" by 5 bytes. "FLAG" is protected by gaps "GAP" of 3 bytes at each of the front and rear thereof. "ALPC" denotes a controlling area for a laser power.
Reference character "SYNC" denotes a synchronizing signal for a data field. The pattern of it includes 3 bytes and is "010000100100001000100010010001001000001001001000". It is disposed subsequently to "VF03".
Reference character "DATA FIELD" denotes a data field in which user data are to be recorded, and has 650 bytes. It is disposed subsequently to the synchronizing signal "SYNC".
Reference character "BUFFER" denotes a margin for rotational jitters and includes 15 bytes. It is disposed subsequently to the "DATA FIELD".
In this manner, one sector is constituted from a total of 746 bytes beginning with the sector mark "SM" and ending with the margin "BUFFER".
FIG. 2 shows construction of the data field. Reference characters "SB1" to "SB3" denote synchronizing signals for the data field recorded in the synchronizing signal "SYNC" described above. Reference characters "RS1" to "RS40" denote each a re-sink and are disposed for each 10 bytes.
Reference character "D1" to "D512" denote each user data (512 bytes), which are disposed in a matrix having 5 columns such that they are arranged, for each successive 5 user data of 5 bytes, in successive rows in each of which they are successively arranged from the left to the right as seen in FIG. 2.
Reference characters "P1,1" to "P3,4" denote each control data (12 bytes) for exchanging operation and so forth, which are disposed in a similar manner subsequently to the user data. Reference character "(FF)" denotes a reserved area, and two such reserved areas (2 bytes) are disposed in a similar manner subsequently to the control data. Reference characters "C1" to "C4" denote each a CRC, and four such CRCs (4 bytes) are provided. The CRCs "C1" to "C4" are error detection codes for the user data "D1" to "D512", control data "P1,1" to "P3,4" and reserved areas "(FF)".
Reference characters "E1,1" to "E5,16" denote each a parity (ECC). The generating direction of the parities is the direction of a column. A (122, 106, 17) Reed-Solomon code.times.5 interleave is used. This code allows correction of errors of up to 8 bytes and allows correction for dissipation of errors of up to 16 bytes.
By the way, FIG. 3A shows a frame format of a compact disk (CD). Referring to FIG. 3A, the frame format includes a frame synchronizing signal SYNC of a 24-bit pattern, a subcoding of one symbol, data of 12 symbols, a P parity of 4 symbols, data of 12 symbols and a Q parity of 4 symbols disposed in this order. Here, one symbol includes 14 bits, and bits for the coupling between symbols (3 bits for each) are not shown. Such one frame corresponds to data of 6 samples (16 bits/sample) of two L and R channels sampled by 44.1 KHz.
The subcoding includes 98 frames making up one block, which is illustratively shown in FIG. 4, while FIG. 5 shows a subcoding format. Referring to FIG. 5, one block is constituted from 96 bytes with two synchronizing patterns of S.sub.0 and S.sub.1 placed at the head thereof. Of 8-bit (after EFM demodulation) data P, Q, R, S, T, U, V and W of the third to 98th frames except the first and second frames corresponding to the synchronizing patterns S.sub.0 and S.sub.1, P and Q are used for accessing, and the remaining 6 bits of R to W are used to a special application for a still picture, a display of characters on a specific background or the like.
In the 98 frames (one sector) constituting one block of such subcoding, data of 588 samples (L0 to L587 and R0 to R587) of the two L and R channels, that is, 2,352 bytes (1 byte=8 bits) are included (FIG. 3B).
In this manner, the sector format for a magneto-optic disk and the block (sector) format for a compact disk both specified by the ISO standards are completely different from each other and cannot be commonly used simply.